This invention generally relates to a composition of matter effective in reacting with airborne or gaseous formaldehyde. Further, the invention provides for a method which irreversibly removes or decreases the amount of formaldehyde from the environment and visually indicates when the formaldehyde removing characteristic is exhausted.
The presence of formaldehyde in the air has long been known to cause discomfort and to be a potential health hazard over prolonged contact. Sources of formaldehyde, especially in the home environment, are numerous. In particular, airborne formaldehyde can be traced to manufacturing processes, particle board, polywood, insulation foam, carpeting, drapes and paneling. While the exact tolerance levels of formaldehyde exposure are vague, it is generally recognized that continuous exposure to even very low levels of formaldehyde can be a source of discomfort even without pronounced irritation. Irritation to the eyes and nasal passages is, however, noticeable at the 0.5 to 1.0 ppm range.
Means by which to remove or lower the levels of airborne formaldehyde have therefore been sought. Attempts to reduce formaldehyde levels have been tried at both the manufacturing stage of potential formaldehyde releasing articles and in the ambient where these articles are installed. For example, U.S. Pat. No. 4,397,756 provides for a method and composition for the reduction of formaldehyde emission in wood panels. This composition comprises urea, a carbohydrate based material and an acidic catalyst. U.S. Pat. No. 4,346,181 attempts to reduce formaldehyde emission from urea formaldehyde foams by incorporating a polymer of acrylamide and/or methacrylamide. U.S. Pat. No. 4,331,438 is directed toward reducing formaldehyde in textile materials by generally treating the material with mixtures of urea and an inert liquid carrier.
While increased measures have been taken to reduce exposure to formaldehyde, there is a continuing need to improve methods for controlling small concentrations of gaseous formaldehyde in the environment. It, therefore, would be desirable to develop a filter-type means whereby the formaldehyde would be irreversibly retained and where the filter upon saturation would give some indication that it should be replaced.